Chaos was once an ordinary Chao, playing in the pool with the others until he absorbed the positive energy from the seven coloured gems around him, he then changed into this liquid creature, Chaos isn't actually evil, he was only very angry with the chief of the Echidna tribe for killing his fellow chao and trying to use the gems for evil, naturaly he used the gems to become a huge liquid creature called Perfect Chaos, he destroyed their entire tribe, eventually a young echidna named Tikal used a spell given to her by her grandmother to seal Chaos and herself inside the Master Emerald for all eternity, that is until Dr. Eggman released them, since then the seven gems where called Chaos Emeralds, named after Chaos Zero, there first user.